“Don’t Worry, He Won’t Get Far on Foot” is Van Sant’s tribute to fellow Portland legend John Callahan, who died in 2010. You remember Callahan: the carrot-haired quadriplegic cartoonist whose squiggly-lined drawings repeatedly crossed the borderline of good taste.

The title refers to the caption of one of his most famous panels, a picture of some cowboys pondering an abandoned wheelchair in the middle of the desert. Before his death, Callahan worked with Van Sant on developing this biopic.

Van Sant’s mainstream side shows in the movie’s surprisingly conventional story line: After his paralyzing accident at age 21, Callahan fights alcoholism and finally embraces the 12-step method, an inspirational process that gets his life together and results in his professional success.

What’s different about “Don’t Worry” is Van Sant’s chockablock approach to the material, which jumps around in time and makes Callahan’s story seem like it’s constantly in the act of unfolding. Which maybe it was.

Ultimately, it works in large part because of a fine cast, and Van Sant’s sensitive work with them. Joaquin Phoenix, who starred in Van Sant’s 1995 film “To Die For,” plays Callahan with committed gusto.

The role is right in Phoenix’s wheelhouse, and he roots through the various sides of Callahan’s personality, by turns obnoxious, terrified, buoyant, and — especially in the scenes where he goes around making amends to people he’s offended in the past — movingly heartfelt.

Rooney Mara plays Callahan’s Swedish friend, and if the film doesn’t seem interested in exploring her background, she’s still appealing in the role.

And in a limited part, Jack Black beautifully navigates a tricky character: the party-hearty pal whose drunk driving results in the accident that changed Callahan’s life.

There’s an especially tasty role for Jonah Hill, as Callahan’s AA sponsor Donnie, a laid-back dude with inherited wealth. In sun-tipped Beach Boy hair and beard, Donnie is blissed-out yet no-nonsense, a fully inhabited portrait of a whimsical but caring soul.

Other odd actors float through, as you’d expect them to in a Van Sant movie: Sonic Youth bassist Kim Gordon, oily character actor Udo Kier and “Portlandia” creator Carrie Brownstein. Somehow these oddball people fit the kind of world Callahan imagined in his cartoons.

Van Sant’s jigsaw-puzzle storytelling means the movie just kind of ends rather than builds to a great climax. It certainly falls short of being a great movie.

But I like the way it deals with subjects that are sometimes ignored in mainstream media — the sexual lives of people with disabilities, for instance — and for two great, basically wordless sequences: One of Donnie dancing alone, and one with the fully addicted Callahan jonesing in his house, unable to reach a precious bottle of booze on a high shelf. The moment of reckoning that follows is one that sometimes feels forced in movies, but in this instance Phoenix and Van Sant had me fully convinced.

“Don’t Worry, He Won’t Get Far on Foot” (3 stars)

Director Gus Van Sant’s tribute to a fellow Portland artist, the carrot-haired quadriplegic cartoonist John Callahan (played with gusto by Joaquin Phoenix). Callahan’s story follows a familiar outline, especially of the recovering-alcoholic variety, but the cast is so good — Jonah Hill is a marvel as Callahan’s blissed-out AA sponsor — that it finally wins you over. With Rooney Mara, Jack Black.